For a long time, it has been a matter of great interest for learners and beginners to know a hitting stress, a hitting angle, or a ball hitting position (where a ball is hit by a face portion of a club head) regarding a practice golf club.
For this reason, without the need for reference documents, there has been a desire among golf players to know a measurement value of a certain type of a sensor or a transducer (an element for converting a physical characteristic into electrical signals, that is, converting one form of energy into another form of energy) attached to the golf club via a display (monitor) or the like.
When no specific embodiment is made clear, an abstract idea about a golf club attached with a sensor and a display unit on its own is not an invention, but something desired. It has been thought for a long time that the desire (problem) has not been practically solved or embodied despite many trials and suggestions since there is no information on the practical technology/method for the embodiment thereof and the accuracy thereof (recognition of existence of long-term unresolved problems).
There have been merely desires, but no complete disclosures containing contents including the practical accuracy based on “specific experiments” such as the arrangement position of sensors having a certain function, a timing of generating a certain calling signal, a calculation process, a display position, a certain display manner/shape, and a correct process through experiments (a long-term unresolved problem).
Meanwhile, although a method of imaging the golf club using a high-speed camera is a reliable method, the cost increases due to an increase in the size of the equipment. Since bright light is required due to the relationship between the sensitivity and the short shutter time, glare or the like influences the hitting action. In addition, since the camera needs to be installed before the ball to shoot the flying ball after hitting, the photographer is in great danger due to the ball flying before him/her, and the camera needs to be protected so that the camera is not broken. Such are the critical defects of this method (critical defects of solving means).
As far as the inventors know, as a specific method of detecting the hitting position of the ball, there is a method of attaching a pressure discoloring sheet to the face portion of the head portion, and determining the ball hitting position on the basis of the discolored sheet. This method has critical defects in that it is necessary to perform an operation of attaching the sheet to the face portion of the club and detaching the sheet after usage every time, the repeated consumption of the pressure sheets is bothersome, and the hitting feeling is different for each sheet (critical defects of solving means).
So far, Patent Documents 1, 2, and 3 disclose a proposal in which an accelerometer is attached to a golf club head, or a torsion meter or a strain meter is attached to a shaft, and a measurement value thereof is displayed on a remote monitor (a display unit: specifically, an oscilloscope).
In addition, there have been attempts to compare and display the repeated swing actions, but the display of the hitting position of the face portion has not been successful. Since many past Patent Documents are cited for reference in such Patent Documents, it is acknowledged that the above-described desire has existed for some time (recognition of existence of long-term unresolved problems).
In Patent Document 4, accelerometers are arranged in three directions perpendicular to each other inside a head, and a predetermined hitting data signal is compared with a current signal so as to estimate a hitting position on the face portion. However, the detail thereof is not shown, and the accuracy is not revealed. Also, regarding the ball, variations in strength, rotation, the type/maker of the ball, humidity, contamination, temperature, or the like should be considered. For this reason, it is not possible to sufficiently display the hitting position with a high accuracy only by using an “accelerometer” (a long-term unresolved problem).
In Patent Document 5, there is a proposal in which data of a graph obtained by a preliminary test result showing the relationship between a driving distance and attenuation of acceleration is displayed on a liquid crystal display (LCD) or a light emitting diode (LED) together with an impact value obtained through one accelerometer (transducer), but this is not the hitting position (recognition of long-term unresolved problems and a disclosure of a display method).
In Patent Document 6, there is disclosed a method of recognizing an existing sound source close to an unknown sound source in such a manner that a preliminarily obtained crest value or arrival time of the existing sound source is compared with a crest value or arrival time of the unknown sound source by using three or more sensors provided to search for a sound source of a structure such as a pressure container, and search for a similarity therebetween (pattern distance).
However, in this method, an object thereof is to search for a sound source in a large object such as a nuclear reactor container, and the existing sound source is compared with the unknown sound source by collecting data of points having a pitch of about 2 m. In the extremely small face portion of the golf club, the arrival time determined by an effective value, an average value, or amplitude of the sound of the existing sound source is substantially the same, and there is no difference therebetween. In addition, the same applies to the magnitude of the sound.
Accordingly, this method is not effective for specifying the hitting position of the golf club (unsuitableness of means). That is, in the method of searching for the three-dimensional position in the pressure container, it is necessary to acquire data of many hitting sound sources in advance. In addition, the accuracy is dependent on the number of sound sources acquired in advance. Furthermore, the detection position is basically obtained by discrete position detection.
In Patent Document 7, there is disclosed a method of measuring a head speed, a swing locus, a face angle, or the like in a manner where a magnetic sensor is provided below a ball setting position in a hitting practice room, and a magnetic signal generated by movement of metal at the time of a swing action is analyzed.
In this method, equipment needs to be prepared below a ball to be hit, the equipment is dependent on many types of largely different clubs, the data for each hitting position is not clear, and simplicity is degraded due to an excessive increase in size of the equipment involved. For this reason, it is not considered that the hitting position is successfully specified. The magnetic sensor is installed at a specific place on the outside of the club instead of the inside thereof, and is increased in scale (critical defects of solving means, and necessity of an underground installation).
In Patent Document 8, there is proposed a method of calculating an impact force and an impact position by concentrically disposing a selective conduction electrode layer and a pressure impedance layer. Although this method can be used in the measurement of sports such as golf or a pitcher's pitching practice, it should be noted that the impact generated upon hitting of the golf ball is of extremely high pressure. Then, regardless of the installation positions of the layers, the durability thereof is low when the layers are installed on the outside of the head, and a high accuracy cannot be obtained due to the impact on the face portion when the layers are installed on the inside of the head. Also, the layers may be broken. These were critical defects. More specifically, the correct hitting position could not be successfully specified (unresolved problems and critical defects of solving means).
In Patent Document 9, there is disclosed a concept in which a pressure sensor is attached to a golf club, and information on a ball is displayed at an appropriate place/portion using a microcomputer. Particularly, it is also mentioned that a hitting force value is measured and displayed by using a “pressure” sensor fixed to the lower portion of the shaft. This is similar to the contents of Patent Documents 1, 2, and 3. In this method, the description for the hitting position is brief and unclear (solving means is merely a desire and unclear).
In Patent Document 10, there is disclosed a method of detecting a hitting position in the forward/backward direction by using a transducer installed on the face portion of a putter in a detachable manner (or embedded in a wood club). In this method, there is a critical defect in that the transducer cannot withstand the repetition of a considerable impact value (estimated to be 1 ton/square centimeter) applied when the transducer comes directly into contact with the ball. In addition, in the specification of the position on the face portion only in the widthwise direction of the face portion (in Patent Document 10, it is thought that the position in the horizontal direction of the face portion can be specified due to the existence of a figure such as a piano keyboard, but the position in the vertical direction of the face portion cannot be specified), the vertical position is not clear, and this method could not successfully specify the hitting position (a long-term unresolved problem).
In Patent Document 11, there is disclosed a golf swing evaluation system in which a maximum hitting force and a hitting position are displayed on a display unit. However, the detailed contents for realizing the object are vague, and the claims are desirously expressed. As a specific example, the arrangement of piezoelectric sensors (pressure sensors) is disclosed, and means for analyzing the relationship between a voltage and a time is also disclosed.
A wristwatch-type display unit provided in the other end of the grip is also disclosed. Due to the viewpoints of durability and accuracy, and the desire without specific calculation for determining the position, it is not thought that the hitting position can be accurately and successfully displayed (a long-term unresolved problem).
In Patent Document 12, all desires are described as above. Then, specifically, a contact piece is provided in the face portion of the golf club so as to reach the inner surface, and a plurality of contact units (rubber pieces) is provided in the inner surface. Accordingly, when the golf club hits the ball, the contact piece is pressed so as to enter an electrical conduction state, thereby detecting the position and displaying the result on the display unit. However, since the calculation, that is, the calculation for a correct display is not clear, and a contact type is used, there are problems of limitations in durability, weight, difficult manufacture process, and many components and arrangement. Also, it is necessary to provide a plurality of contact pieces connecting from the outside to the inside of the face portion in the entire surface (critical defects in solving means and a plurality of holes in the face portion).
In Patent Document 13, there is disclosed a desire for estimating a driving distance and displaying a hitting position on display means of a liquid crystal type or a light emitting type provided in a shaft by using a plurality of detection means such as impact sensors for detecting the ball hitting position on the head, and a concept of the driving distance of a ball in accordance with the hitting position.
Since there is a problem in the installation toward a front surface of a metal plate of a head, it is supposed that there is no installation toward the front surface. In the installation toward the rear surface of the metal plate, since an impact pressure acts on the entire metal plate, it is not apparent how to detect and calculate the impact pressure, and thus this is merely a desire. In addition, since many various sensors having different properties are arranged, it is further deemed that this method is merely a desirous application (insufficient and desirous solving means).
In Patent Document 14, there is disclosed an analysis of sound by specifically utilizing the merit of a concentric arrangement of sensors (a problem to be solved by present invention cannot be solved by desirous solving means disposed in a concentric arrangement).
In addition, in Patent Documents 12 and 15 to 19, there is disclosed a method of recognizing the position on a sensor generating the largest signal or the vicinity thereof as a hitting point by disposing a group of sensors (in a matrix shape or a concentric shape or the like) in a face portion. Here, since many sensors are required, the weight of the golf club increases, and the attachment to the golf club is difficult. Also, since the sensors are installed at the hitting portion, the sensors are easily broken by impact, and the cost increases.
In addition, in Patent Document 21, a hitting position is obtained from a natural vibration frequency (frequency analysis) of a hitting sound. It is difficult to distinguish the natural vibration frequency, and it is not possible to obtain a high accuracy within several mm. Alternatively, it seems that this method may not be realized.
Patent Document 1: U.S. Pat. No. 3,270,564
Patent Document 2: U.S. Pat. No. 3,792,863
Patent Document 3: U.S. Pat. No. 3,806,131
Patent Document 4: U.S. Pat. No. 3,945,646
Patent Document 5: U.S. Pat. No. 4,088,324
Patent Document 6: Japanese Unexamined Patent Application, First Publication No. S59-231462
Patent Document 7: U.S. Pat. No. 4,615,526
Patent Document 8: U.S. Pat. No. 4,659,090
Patent Document 9: Japanese Unexamined Patent Application, First Publication No. S62-192186
Patent Document 10: U.S. Pat. No. 4,898,389
Patent Document 11: U.S. Pat. No. 4,991,850
Patent Document 12: Japanese Unexamined Utility Model Application, First Publication No. H04-92273
Patent Document 13: Japanese Unexamined Patent Application, First Publication No. 2000-84133
Patent Document 14: Japanese Unexamined Patent Application, First Publication No. 2004-81407
Patent Document 15: Japanese Unexamined Patent Application, First Publication No. H03-146079
Patent Document 16: Japanese Unexamined Patent Application, First Publication No. H03-146080
Patent Document 17: Japanese Unexamined Patent Application, First Publication No. S56-31766
Patent Document 18: Japanese Examined Utility Model Application, Second Publication No. H06-11027
Patent Document 19: Japanese Unexamined Patent Application, First Publication No. S57-175371
Patent Document 20: Japanese Unexamined Patent Application, First Publication No. S59-183773
Patent Document 21: Japanese Unexamined Patent Application, First Publication No. H10-267744